A hydrocarbon resource may be particularly valuable as a fuel, for example, gasoline. One particular hydrocarbon resource, bitumen, may be used as a basis for making synthetic crude oil, which may be refined into gasoline by a process called upgrading. Accordingly, bitumen, for example, may be relatively valuable. More particularly, to produce 350,000 barrels a day of bitumen based synthetic crude oil would equate to about 1 billion dollars a year in bitumen. Moreover, about 8% of U.S. transportation fuels, e.g., gasoline, diesel fuel, and jet fuel, are synthesized or based upon synthetic crude oil.
In the hydrocarbon upgrading or cracking process, hydrogen is added to carbon to make gasoline, so, in the case of bitumen, natural gas is added to the bitumen. Natural gas provides the hydrogen. Bitumen provides the carbon. Certain ratios and mixes of carbon and hydrogen are gasoline, about 8 carbons to 18 hydrogens, e.g. CH3(CH2)6CH3. Gasoline is worth more then either bitumen or natural gas, and thus the reason for its synthesis.
One process for cracking the hydrocarbons is fluid catalytic cracking (FCC). In the FCC process, hot bitumen is applied to a catalyst, for example, AlO2, at 900° C. with a relatively small amount of water to form synthetic crude oil. However, the FCC process has a limited efficiency, about 70%. The residual, also known as coke, is worth far less. Moreover, coke residues stop the FCC process, and there is an increased risk of fires and explosions. The FCC process also has a poor molecular selectivity, and produces relatively high reactant emissions, especially ammonia. The catalyst used in the FCC process also has a relatively short lifespan.
According to the U.S Energy Information Administration the producible oil reserves of the United States may be 21 billion barrels and the total oil in place may be 134 billion barrels. The ratio of producible oil reserves to the total oil in place may be referred to as the recovery factor. The recovery factor may be improved by enhanced oil recovery (EOR) techniques, such as water flooding or by heating the hydrocarbon reservoir. Conducted heating in hydrocarbon reservoirs may be relatively slow however, for example, the thermal conductivity of wet Athabasca oil sand is about 0 watts per meter degree Kelvin, and dry Athabasca oil sand is about 1.5 watts per meter degree Kelvin. Thus, Athabasca oil sand, which is almost a thermal insulator compared to copper, for example, which has a thermal conductivity of 401 watts per meter degree Kelvin. EOR by steam injection may initially require relatively slow conducted heating to initiate the convective flow that later conveys the steam heat. Many steam assist gravity drainage (SAGD) well systems fail to start due to thief zones, or for reasons unknown. Radio frequency heating may address low thermal conductivity and low permeation in hydrocarbon ore, as electromagnetic energies do not use thermal conductivity or convection for penetration.
Several references disclose the application of RF to a hydrocarbon resource to heat the hydrocarbon resource, for example, for cracking. In particular, U.S. Patent Application Publication No. 2010/0219107 to Parsche, which is assigned to the assignee of the present application, discloses a method of heating a petroleum ore by applying RF energy to a mixture of petroleum ore and susceptor particles. U.S. Patent Application Publication Nos. 2010/0218940, 2010/0219108, 2010/0219184, 2010/0223011, 2010/0219182, all to Parsche, and all of which are assigned to the assignee of the present application disclose related apparatus for heating a hydrocarbon resource by RF energy. U.S. Patent Application Publication No. 2010/0219105 to White et al. discloses a device for RF heating to reduce use of supplemental water added in the recovery of unconventional oil, for example, bitumen.
Several references disclose applying RF energy at a particular frequency to crack the hydrocarbon resource. U.S. Pat. No. 7,288,690 to Bellet et al. discloses induction heating at frequencies in the range of 3-30 MHz. Application Publication No. 2009/0283257 to Becker discloses treating an oil well at a frequency range of 1-900 MHz and no more than 1000 Watts, using a dipole antenna, for example.
Application of RF to a hydrocarbon resource to heat the hydrocarbon resource for cracking, may, in many instances, not be particularly efficient as a relatively large amount of energy may be lost in the heating process. Additionally, application of RF energy may result in irregularities in the heating process, such as, inconsistent temperatures or hot spots.
U.S. Patent Application Publication No. 2010/0219184 to Parsche, which is also assigned to the assignee of the present application, discloses an RF heater for controlling the heating to certain materials of the hydrocarbon resource. The Parsche '184 application discloses a cyclonic vessel that has a conical wall and a conically wound RF conductor adjacent the conical wall. The RF conductor couples to an RF source to heat hydrocarbon resources within the cyclonic vessel.
U.S. Pat. No. 7,798,220 to Vinegar et al. discloses superconducting cables coupling to an AC or modulated DC current source. The superconducting cables are nitrogen cooled. The superconducting cables couple to heaters, which are within a wellbore.
Further improvements in the application of RF energy for heating, and more particularly, hydrocarbon resource extraction and upgrading may be desirable. For example, it may be desirable to increase the efficiency of the bitumen to gasoline conversion process, i.e. upgrading, by making it quicker and cheaper.